A pressure sensor designed to be mounted on a printed circuit board is known to be comprising:
a body, wherein tab terminals for connector connection are insert-molded, or wherein coil terminals-cum-soldering fixed terminals which are inserted into a printed circuit board are insert-molded;
a coil spring adjusting screw which is screwed into said body;
a coil which is wound around said body;
a magnetic body which moves relative to said coil;
a diaphragm which has a support for said magnetic body projected approximately at the center on one side and has plural ring-shaped reinforcing ribs on the other side;
a coil spring which restores said diaphragm;
a cover with pressure inlet pipe.
It is disclosed in Japan's Published Unexamined Patent Application No. 23394/99, from page 4 to 5, FIG. 2.
Also, it is public known technology to form small bosses on said cover so that said cover with pressure inlet pipe and the ring-shaped reinforcing ribs formed on the diaphragm are not adhered to each other. It is disclosed in Japan's Utility Model Gazette No. 47094/77, from page 1 to 2, FIG. 2.
However, although it is possible to form small bosses if said cover has a large diameter, it is almost impossible to form the bosses on said cover with a small diameter. So, it is common that no bosses are formed on said cover with a small diameter.
Recently, material forming a diaphragm is shifting from EPDM (ethylene-propylene rubber) to silicone rubber. It is disclosed in Japan's Unexamined Patent Application No. 170393/01.
This is because of an advantage that silicone mostly meets requirements for a diaphragm (temperature characteristics) and that it has little problem of adherence to said cover.